1. Field of the Invention
The present invention relates to an exposure apparatus, which is used in a photolithographic process that manufactures devices like semiconductor devices, as well as to an exposure method and the like.
2. Description of Related Art
In a photolithographic process that manufactures devices, such as semiconductor devices, thin film magnetic heads, and liquid crystal display devices, an exposure apparatus is generally used to transfer an image of a pattern formed on a photomask or a reticle onto a substrate, which is coated with a photosensitive agent, such as a photoresist. As the capacity of semiconductor memory has increased year by year along with the speed and the levels of integration of CPU processors, there has been increasingly greater demand for higher levels of integration and increased fineness of the resist patterns formed on substrates by exposure apparatuses. On the other hand, the increased levels of integration and fineness of the patterns has given rise to an increased defect rate and decreased yield when exposure conditions change even slightly.
Consequently, in an exposure apparatus, defects in the pattern line widths, which become nonuniform due to unevenness in the illuminance, are prevented by uniformizing the cumulative amount of exposure. In particular, within scanning type exposure apparatuses, which relatively scan a mask and a substrate with respect to a slit-shaped illumination light to transfer a pattern formed on the mask onto the substrate, a variable slit apparatus has been proposed that uniformizes the cumulative amount of exposure by changing portions of the slit width of the illumination light, as disclosed in, for example, Japanese Published Unexamined Patent Application No. H10-340854, Japanese Published Unexamined Patent Application No. 2000-82655, and the like.
The technology discussed above changes portions of the slit width of the illumination light by lining up a plurality of blades in the longitudinal direction of the slit-shaped illumination light and linking each blade to an actuator, which is then driven. Furthermore, to precisely eliminate exposure unevenness caused by the illuminance unevenness, it is preferable to finely control the slit width of the illumination light by using numerous blades in order to increase the number of places (positions in the longitudinal direction) at which the slit width can be modified.
Nevertheless, there is a problem in that the increased number of blades commensurately increases the number of actuators, which increases the complexity of controlling the actuators and also decreases the throughput of the exposure apparatus because of the increased time needed to change the shape of the illumination light. In addition, there is a problem in that the heat generated by the increased number of actuators adversely affects the exposure accuracy of the exposure apparatus.
A purpose of some aspects of the present invention is to provide a variable slit apparatus, which can rapidly change the shape of the slit width of the illumination light while finely controlling the shape of the slit-shaped illumination light, an illumination apparatus that uses the same, an exposure apparatus, an exposure method, and a device fabrication method.